(CNN)There's nothing like a Supreme Court vacancy to get people in Washington talking about the Senate.

It's less clear, however, whether the voters who will decide control of the Senate nine months from now are attuned to that conversation, especially since the ideological makeup of the court is not in the balance.
Justice Stephen Breyer's decision to retire came as President Joe Biden's approval rating stood at 42%, with 55% disapproving, according to CNN's average of six recent national polls. The best scenario for Democrats is that the vacancy and Biden's pledge to nominate a Black woman will help drive base enthusiasm and remind moderates who care about abortion rights, for example, of what's at stake in the battle for the Senate. But that may be a lot of theoretical dot-connecting for most Americans preoccupied with high prices at the pump and the checkout line.

Still, the seat most likely to flip partisan control is the place where Democrats see the Supreme Court vacancy as having perhaps the biggest impact. That's not a new development: Pennsylvania has led the list since CNN started ranking the 2022 races nearly a year ago. But it speaks to the demographics Democrats need to turn out in the Keystone State -- their urban base and suburban voters.

The ranking is based on CNN's reporting and fundraising data, as well as historical data about how states and candidates have performed. Fundraising reports for the fourth quarter of 2021, which were due to the Federal Election Commission by Monday, showed some Democrats raising massive sums of money, while some Republican candidates poured significant personal wealth into their campaigns. As the year progresses, more polling and advertising spending data will become bigger factors in the ranking.
While Pennsylvania still leads the list, Republicans are feeling more confident about the seat, which GOP Sen. Pat Toomey is vacating, than they have in months, thanks to some new candidates. But it remains a question, as is the case in several other races, how much embracing former President Donald Trump in the primary comes back to haunt the eventual GOP nominee in the general election in a state Biden won in 2020.
As he resumes his campaign-style rallies, with a heavy focus on his 2020 election lies, Trump is signaling that he won't be sitting 2022 out quietly, even if he's not on the ballot. The jockeying for his support has already led to massive spending -- especially in Pennsylvania, where the GOP primary has attracted $18 million, mostly in December and January alone, according to a CNN analysis of AdImpact data.
"I still say it's 50-50," Senate Minority Leader Mitch McConnell told CNN's Manu Raju last week about the GOP's chances of flipping the chamber.
The Kentucky Republican backed the bipartisan infrastructure law, one of Biden's biggest achievements to date, but he's standing in the way (along with two moderate Democrats) of the President's other priorities, such as his social spending and climate change plan and voting rights legislation, both of which stalled in the Senate.

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Vulnerable Democratic incumbents on this list -- Sens. Mark Kelly, Catherine Cortez Masto, Maggie Hassan and Raphael Warnock -- all voted in favor of eliminating the filibuster to pass voting rights legislation. While taking that position has become a new litmus test of sorts in Democratic primaries (again, see Pennsylvania), and some Republicans are attacking Democrats over it, it's far from clear that the fate of the 60-vote threshold is a salient issue for American voters.
There's been plenty of effort to get voters' attention. Candidates and outside groups have already spent twice as much on TV and radio ads as they had at similar points in the 2018 and 2020 cycles, according to a CNN analysis of AdImpact data.
Look for that spending to increase quickly ahead of spring primaries, with the first big Senate contest of the year (Ohio) happening on May 3. Until then, stay tuned for more updates to this ranking.
Here are the top 10 Senate seats most likely to flip as of this month:

1. Pennsylvania

Incumbent: Republican Pat Toomey (retiring)

Pennsylvania remains the seat most likely to flip, although Republicans feel better about holding retiring Sen. Pat Toomey's seat now that the Trump-backed candidate is out of the race and several new candidates have jumped in.
"We have an embarrassment of riches," McConnell told Raju in late January. The biggest new name is hedge fund executive David McCormick. A former Treasury official in the George W. Bush administration who lived in Connecticut for years, McCormick has rolled out ads trying to convince voters that "his Pennsylvania roots will keep him grounded." He's the husband of Dina Powell McCormick, who was Trump's deputy national security adviser. Sean Parnell, the Trump endorsee who suspended his campaign after a public custody battle that was generating worrisome headlines for the GOP, quickly backed McCormick, as did Sen. Ted Cruz of Texas, who recently rallied with him in the state.
McCormick and his allies are already in a sniping contest with Dr. Mehmet Oz, who entered the race late last fall and had loaned his campaign more than $5 million, according to his recent FEC filing. Honor Pennsylvania, an anti-Oz group, is attacking the former talk show host as a "Hollywood liberal." (Like McCormick, Oz recently lived out of state, in New Jersey.) American Leadership Action, a pro-Oz group, is going after McCormick's business record, as is Oz's campaign.
There were already Republicans running here -- allies of businessman Jeff Bartos, for example, are attacking the two newcomers as carpetbaggers -- and Carla Sands, who was ambassador to Denmark under Trump, loaned her campaign another $500,000 in the fourth quarter.
While Democrats are enjoying watching Republicans duke it out, they have their own crowded primary. Lt. Gov. John Fetterman is still the fundraising leader, raising $2.7 million in the fourth quarter. Rep. Conor Lamb -- who, like Fetterman, is from the western part of the state -- has picked up some labor endorsements and the backing of the mayor of Philadelphia. He finished ahead of the other candidates in a state party committee vote last weekend but fell short of the threshold for an endorsement.

2. Georgia

Incumbent: Democrat Raphael Warnock

After winning a special election runoff last winter that helped flip the Senate, Democratic Sen. Raphael Warnock never slowed down. He raised $9.8 million in the fourth quarter as he seeks a full six-year term in November. Only a sum like that could make the nearly $5.4 million that Republican challenger Herschel Walker raised seem paltry. Since Biden won the state in 2020, Georgia has remained one of the most interesting political battlegrounds that's also home to a high-profile gubernatorial race and is ground zero for the fight for voting rights, which Democrats hope could energize turnout on their side. With the national spotlight on his state, Warnock isn't likely to be hurting for money anytime soon.
And while staggering Democratic fundraising hasn't always translated to success (see South Carolina in 2020 or Texas in 2018), public polling suggests this race is competitive. A recent Quinnipiac University poll showed no clear leader, with Walker at 49% and Warnock at 48% among registered voters. Republicans are feeling confident about this race now that McConnell and Trump are united behind Walker, even if the former NFL star remains largely untested as a candidate, and because the national environment has looked increasingly strong for them. Biden's job approval rating in the Peach State in that Quinnipiac poll, for example, was 36%. But Democrats take heart that Warnock's job approval was a higher 47%. With Senate races so nationalized these days, Warnock will need to continue to overperform Biden -- as he did in 2021 -- if he's going to survive in November, regardless of how many millions he raises.

3. Wisconsin

Incumbent: Republican Ron Johnson

The big news here is GOP Sen. Ron Johnson is running for reelection, which reassured Republicans and enthused Democrats. Republicans are glad to be avoiding another messy primary, and they're thankful Johnson didn't wait even longer to make his announcement. In a video explaining his decision, Johnson says he intended for his current term to be his last but cannot "walk away" after seeing "the Democrats in total control."
Democrats, however, are thrilled that Johnson -- who has continued to make controversial and misleading statements about Covid-19 and January 6 -- is running. They believe he's a damaged enough incumbent that it will be easier to flip this seat with him in it than if he weren't. Senate Majority PAC, the preeminent Democratic super PAC, quickly attacked Johnson for being "deep in the swamp." Johnson's announcement also prompted the Democratic Senatorial Campaign Committee to launch its first TV ad of the cycle, hitting him for "looking out for himself."
Republicans think a strong national environment will help them hold on to this seat, especially if they can paint the eventual Democratic nominee as too far left for the state, which backed Biden by less than a point in 2020. They're excited about the prospect of running against Lt. Gov. Mandela Barnes, for example, who has the support of Sen. Elizabeth Warren of Massachusetts. Barnes raised $1.2 million in the fourth quarter -- which is more than Johnson's $711,000 but lower than some Democratic challengers across the country. And he faces a crowded primary, including Milwaukee Bucks executive Alex Lasry, who loaned his campaign about $1.5 million in the fourth quarter and has been running a series of ads on TV.

4. Arizona

Incumbent: Democrat Mark Kelly

Democratic Sen. Mark Kelly, like Warnock in Georgia, continues to post impressive fundraising numbers as he runs for a full six-year term in November. Kelly raised nearly $9 million in the last quarter. That, on its own, should put Republicans on notice in an increasingly purple state that Biden narrowly won in 2020. But unlike Georgia, where the GOP has largely coalesced around one candidate, Republicans here face a real headache with a messy candidate field ahead of the August primary. There have been renewed rumors about Gov. Doug Ducey running, which would please McConnell and national Republicans, but he's a frequent target of Trump and doesn't appear to have made any moves ahead of the April filing deadline.
That leaves Attorney General Mark Brnovich, whose fundraising continues to be underwhelming (he raised about $800,000 last quarter) and venture capitalist Blake Masters, among several others, duking it out. Masters raised nearly $1.6 million, but he also has the advantage of a Peter Thiel-backed super PAC touting him as a "Trump conservative." Based on the advertising in the state -- which has already crept past $30 million, according to CNN's analysis of AdImpact data as of Friday -- Republicans are leaning into the Trump loyalty contest. Solar energy entrepreneur Jim Lamon, for example, who loaned his campaign $3 million in the fourth quarter, is going all-in on Trump's claims of a rigged election.
Regardless of their nominee, Republicans think it's a winnable race, especially if the national environment continues to look bleak for Biden and other Democrats, and they're eager to go after Kelly's voting record and exploit the differences between him and his more moderate Democratic Arizona colleague, Sen. Kyrsten Sinema.

5. Nevada

Incumbent: Democrat Catherine Cortez Masto

This is one of the few contests, like Georgia, where Trump and McConnell have already united behind the same candidate. In Nevada, it's former state Attorney General Adam Laxalt, the grandson of the former governor and senator with the same last name. The GOP's ability to coalesce around him ahead of the June primary could be critical to winning the seat, but he still faces competition. Retired Army Capt. Sam Brown raised about $1 million in the fourth quarter, just shy of Laxalt's $1.3 million.
Republicans are hopeful that Biden's sagging approval ratings and voters' anxieties will help them in the state, which has seen its share of pandemic and inflation woes.
"I don't know if it's the President, or what happened, but (under Trump) it was so much better," one Nevada voter who has recently voted for Democrats told CNN's Maeve Reston in early January.
Sen. Catherine Cortez Masto, the former chair of the Democratic Senatorial Campaign Committee, raised about $3.3 million last quarter and hasn't yet really reintroduced herself to voters. Democrats have long believed that abortion could be a salient issue here -- especially since Laxalt's opposition to abortion rights puts him at odds with the state's most recent GOP governor -- and are hoping the Supreme Court vacancy will help bring more attention to that contrast by reminding voters what's at stake. But Republicans' inroads with Hispanics, combined with the state's non-college-educated White population, make this race among the most competitive.

6. North Carolina

Incumbent: Republican Richard Burr (retiring)

Trump's endorsement in this race nearly eight months ago has yet to clear the GOP field, with none of the candidates posting stellar fundraising. In fact, former Rep. Mark Walker announced last week that he would carry on with his Senate campaign rather than drop down to a House race with the possibility of an endorsement from the ex-President. Rep. Ted Budd, Trump's pick for Senate, raised $968,000 in the fourth quarter and continues to introduce himself to voters statewide, while the Club for Growth's political arm spends big to help him. That includes going hard after former Gov. Pat McCrory, who raised $748,000. Combat veteran Marjorie K. Eastman raised $423,000 and is less well known but has benefited from nearly $1 million in outside spending from a group called Restore Common Sense. The delay in the state's primaries from March to May, thanks to redistricting litigation, will give Republicans more time to sort out their field.
Democrats, meanwhile, have a prohibitive favorite in former state Supreme Court Chief Justice Cheri Beasley after other major candidates dropped out. She raised $2.1 million in the last quarter. While Republicans likely start with the advantage in this state that Trump carried by about a point in 2020, Democrats are hopeful Beasley can energize minority turnout in a non-presidential year.

7. New Hampshire

Incumbent: Democrat Maggie Hassan

Democratic Sen. Maggie Hassan got a huge break when Republican Gov. Chris Sununu decided late last year to run for reelection rather than challenge her. Besides retired Army Brig. Gen. Don Bolduc, several other Republicans are now hoping to take on Hassan, although none of Sununu's stature. Londonderry Town Manager Kevin Smith, who unsuccessfully sought the GOP gubernatorial nod in 2012, announced his campaign last month. State Senate President Chuck Morse followed over the weekend, riding a skid-steer loader into his snowy announcement event, WMUR reported. McConnell singled out Morse in his interview with CNN last week, saying, "We think we'll have a good candidate there."
Democrats have done well in the Granite State in recent federal elections, with Biden carrying the state by 7 points in 2020. But his approval rating slipped last fall, giving Republicans hope they'd unseat Hassan even without their preferred candidate. Biden's numbers had somewhat improved by mid-December, returning to July levels, according to the most recent University of New Hampshire Granite State Poll. Hassan, who raised $3.2 million in the last quarter, isn't in as competitive a race as she could have been had Sununu thrown his hat in the ring, but she still has to hope that the national environment doesn't endanger her. Only 28% of New Hampshire residents in that Granite State Poll, for example, said things in the US "are headed in the right direction."

8. Florida

Incumbent: Republican Marco Rubio

GOP Sen. Marco Rubio is running for a third term in a state that has favored Republicans recently. (Trump carried it by 3 points in 2020.) That means he starts as the favorite, but Democratic Rep. Val Demings, who was a contender for Biden's running mate, has been an impressive fundraiser. She raised about $7.2 million in the fourth quarter -- more than Rubio's $5.2 million, although he ended 2021 with more cash on hand. Demings will need the money to introduce herself statewide across expensive media markets.
Rubio has recently been touting his support from law enforcement, trying to counter any advantages Demings might bring to the race as a former Orlando police chief. The congresswoman responded last week by calling Rubio a "lifelong politician," saying that during her tenure with the police she had helped respond to "some dark, scary places" while he was "home in his bed sleeping," according to the South Florida Sun Sentinel.

9. Ohio

Incumbent: Republican Rob Portman (retiring)

The Republican primary field to replace retiring GOP Sen. Rob Portman remains unsettled ahead of the May primary as candidates and their allies frantically put out polls to try to shape their own narratives of the race. The Club for Growth's political arm is spending for former state Treasurer Josh Mandel, attacking "Hillbilly Elegy" author J.D. Vance and former state party Chair Jane Timken. Almost all the candidates, including a couple of big-spending businessmen, are leaning heavily into Trump's rhetoric, creating a sharp distinction from the senator they're hoping to succeed.
Vance claimed in a tweet thread on the anniversary of the US Capitol insurrection that many of the rioters in a DC jail are "political prisoners," adding, "They are our people." He also recently secured the endorsement of controversial GOP Rep. Marjorie Taylor Greene of Georgia, which he likely hopes will blunt some of his past public criticism of Trump. State Sen. Matt Dolan was the rare candidate to describe January 6 as "an attack on American democracy" in a statement on the one-year anniversary, calling out "fake conservatives willing to sacrifice our most sacred text, the Constitution, in favor of political expedience." He's invested a stunning $10.5 million of his own money into his campaign (mostly in contributions, not loans) but faces a steep uphill battle in a GOP primary that revolves around Trump.
On the Democratic side, Rep. Tim Ryan, who raised $2.9 million last quarter, has largely consolidated support, but Ohio, which Trump carried by 8 points, remains a tough state for anyone in his party who's not Sen. Sherrod Brown.

10. Missouri

Incumbent: Republican Roy Blunt (retiring)

Missouri is different from most of the states on this list in that it really wouldn't be here if it weren't for one man. "Missouri is potentially challenging depending on the outcome in the primary," McConnell told Raju. Former Gov. Eric Greitens, who resigned from office following a probe into allegations of sexual and campaign misconduct, threatens to put in play a red state that Trump won by 15 points in 2020. He's trying to align himself with Trump, and Kimberly Guilfoyle, the fiancée of the ex-President's son, is his campaign's national chair.

Greitens faces a handful of Republicans also trying to secure Trump's support ahead of the August primary. Rep. Billy Long, for example, ran an ad about Democrats "rigging the election." State Attorney General Eric Schmitt recently announced lawsuits against school districts with masking rules, which is becoming a conservative rallying cry as the third year of the pandemic gets underway. GOP Rep. Vicky Hartzler -- the only woman in the race -- hasn't hesitated to go after Greitens, taking an implicit jab at his extramarital affair in her first ad released last fall.
The fear is that Greitens could jeopardize the general election much like GOP nominee Todd Akin did in the 2012 Senate contest. And the more Republicans in the race, the more splintered the primary vote will be, thereby lowering the threshold Greitens would need to win the nomination. Democrat Lucas Kunce raised $710,000 in the fourth quarter -- more than any of the Republicans excluding personal loans. But the Marine veteran will need more than money to make the race go his way.

CNN's David Wright contributed to this report.

Source: https://edition.cnn.com/